On Saturday, PowerNet said three of its networks were badly disrupted by stormy weather overnight, and it warned affected customers to prepare for extended blackouts.
They were OtagoNet, Electricity Invercargill and The Power Company, which services Southland.
PowerNet said teams were working to restore power, but faced challenging conditions, and the safety of their crews came first.
The teams at work on Saturday had stopped as darkness fell, but were planning to start again at first light on Sunday.
Some customers could remain without power into Monday and people who were medically dependent on electricity should plan accordingly, they said.
By 2pm on Saturday, PowerNet's website said only 150 properties were still without power, down from about 8000 customers earlier in the weekend.
The website showed the remaining outages were east of Invercargill.
Firefighters were kept busy across the South dealing with callouts owing to strong winds from Friday into Saturday, including calls for help with roofs lifting off houses and fallen trees.
In Dunedin, some Otago Peninsula residents were without power for most of the day, and outages were also reported in parts of South Otago.
MetService forecasters had issued strong wind warnings, including for gusts up to 130kmh in places, although the orange warning was due to expire at 3pm on Saturday.
In the North Island, an orange strong wind warning for Hawke's Bay, from Napier south and down to the Tararua District, was expected to be in place until 10pm Sunday, and an orange wind warning for the Chatham Islands was expected to last until 3pm on Sunday. Those areas could see winds up to 130kmh, with thunderstorms possible in the Chathams.
A heavy swell warning was in place for parts of Wairarapa, from 1am Sunday until late Monday.
